Thermal cut-out.



UNITED STATES PATENT OFFICE.

CHARLES I, STEINMETZ, OF SCHENECTADY, NElV YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NEIV YORK.

THERMAL CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 636,578, dated November '7, 1899.

Application filed August '7, 1899.

To all whom it may concern:

Be it known that 1, CHARLES P. STEINMETZ, a citizen of the United States, residing at Schenectady, count-y of Schenectady, State of New York, have invented certain new and useful Improvements in Thermal Cut-Outs, (Case No. 1,142,) of which the following is a specification.

This invention relates to automatic circuit interrupters or cut-outs. In devices of this kind employed with high potential currents it is necessary to produce a sudden interruption of the are formed by the action of the cut-out in opening the circuit in order to prevent injury to the circuit-terminals. A com mon provision is to insert in the circuit a fuse with a spot of low conductivity at a point distant from either terminal at which the fuse will first give way and create by some auxiliary means an expulsive action on the are by which when the fuse blows it will be extinguished, thereby interrupting the circuit before the terminals have been damaged. My invention relates generally to this type of devices, though it is not necessary that a fusible interrupter should be employed, as the expulsive means I employ to extinguish the are are dependent only upon a rise of temperature in the cut-out device, upon which an explosive material is raised to a reacting temperature and the circuit interrupted.

In the specific form herein set forth my invention comprises the employment of a metallic acetylide. Certain compounds of acetylene with metals when dried explode at very low temperatures. For example, cupric acetylide (C CU XH O) when dried explodes at a heat of from to centigrade, leaving a residue of black powder containing charcoal and copper. So also silver acetylide and gold acetylide explode at low temperatures. I employ a body of one of these compounds in such relation to a conductor inserted in the circuit to be interrupted that when the conductor carries an excessively large current it will heat sufficiently to explode the compound, the explosion destroying a part of the conductor and violently interrupting the arc, which forms at the instant of circuit rupture.

The best mode of carrying out my invention is to inclose a conducting-wire of such Serial No. 726,381. (No model.)

' current-carrying capacity that it will heat upon carrying an excessive current for the circuit in which it is installed within a fragile tube containing an explosive acetylide. The tube may be provided with openings and lined with a thin material which will easily give way, the result being that upon the sudden accumulation of pressure due to the explosion the cond uctor is ruptured or destroyed and the arc extinguished by being blown through the openings or outwardly from the tube if the latter be shattered.

The features of novelty of my invention will be more particularly described hereinafter and will be definitely indicated in the claims appended to this specification.

In the drawings, which illustrate several embodiments of my invention, Figure 1 is a view illustrating a thermal cut-out inclosed within a perforated tube containing a portion of the explosive compound. Fig. 2 is a pen spective View of such a device. Fig. 3 is a modification in which a fragile tube without perforations is employed. Fig. 4 is a longitudinal sectional View of such a tube, and Fig. 5 is a cross-sectional View.

1 and 2 represent the terminals of an electric circuit, between which may be inserted a cut-out such as hereinabove referred to. This comprises a conductor, which may be a wire, easily-fusible wire or not, as shown at 3, secured in conductive relation to two end caps of metal at 5, slipped over the ends of the fragile tube 6. The latter may be made of fiber, pasteboard, or other material which will afford suificient stiffness for ordinary service and will at the same time be a non-conductor of electricity. The tube may be filled around the conductor with an explosive acetylide compound, as indicated at 7, or the conductor may be coated with this compound and held in place byanysuitable vehicle. The compound may be handled with perfect safety when wet; but when dry, in which condition it still contains its water of crystallization, as its formula indicates, is highly explosive on percussion or when raised to a comparatively moderate temperature. I preferably dry it carefully before introducing it into the tube, and the latter may be lined with thin paper, as indicated at S, and particularly so if perforated,

IOO

as in the design shown in Figs. 1 and 2. As thus organized it will be evident that upon an excessive current traversing the conductor between the cut-out terminals the latter will heat, and on attaining a temperature which may be considerably below fusion and much below red heat or the point of reaction for ordinary explosives will explode the acetylide and rupture the circuit. The reaction is effected without the accompaniment of any noxious gases. If desired, the conductor may be provided with a weak spot of low currentcarrying capacity, the explosive being placed at the sides, where the are will spread after the fuse blows. The action in such a case will be to permit an arc to form and then blow it out and shatter the fuse ends by the explosive compound.

l/Vhat I claim as new, and desire to secure by Letters Patent of the United States, is

1. An electric cut-out, comprising a conductoradapted to heat under a predetermined strength of current, and a body of an explosive acetylide compound in heat-conductive relation to the conductor.

2. An electric cut-out comprising a cond uctor adapted to heat u n dcr a predetermined strength of current, and a body of acetylide of copper in heat-conducth'e relation to the conductor.

3. An electric cut-out comprising a conducting-wire adapted to be connected to the terminals of the circuit and to heat under excessive current in said circuit, a casing around said conductor, and'an explosive acetylide between the conductor and easing.

i. An electric cut-out comprising a closed fragile tube provided with conducting ends between which is inserted a wire adapted to heat under excessive current in the circuit in which it is placed, and a body of acetylide of copper between the conductor and the tube.

5. A cut-out for an electric circuit comprising a perforated tube containing a thin electric conductor adapted to be connected to two circuit-terminals, and a body of acetylide of copper in heat-conductive relation to the cond uctor.

6. A cut-out for an electric circuit, comprising a perforated tube, a thin lining therefor, a thin electric conductor within the tube, adapted to be connected in an electric circuit, and a body of acetylide of copper between the conductor and the lining.

In witness whereof I have hereunto set my hand this 1th day of August, 1899.

CHARLES P. STEINMETZ.

Witnesses:

EEN AMIN B. HULL, Manna E. JAconsoN. 

